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    Subject[PATCH RFC 4/7] kvm: x86: Add new ioctls for XSAVE extension
    Date
    The static xstate buffer kvm_xsave contains the extended register
    states, but it is not enough for dynamic features with large state.

    Introduce a new capability called KVM_CAP_X86_XSAVE_EXTENSION to
    detect if hardware has XSAVE extension (XFD). Meanwhile, add two
    new ioctl interfaces to get/set the whole xstate using struct
    kvm_xsave_extension buffer containing both static and dynamic
    xfeatures. Reuse fill_xsave and load_xsave for both cases.

    Signed-off-by: Jing Liu <jing2.liu@linux.intel.com>
    ---
    arch/x86/include/uapi/asm/kvm.h | 5 +++
    arch/x86/kvm/x86.c | 70 +++++++++++++++++++++++++--------
    include/uapi/linux/kvm.h | 8 ++++
    3 files changed, 66 insertions(+), 17 deletions(-)

    diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
    index 89e5f3d1bba8..bf785e89a728 100644
    --- a/arch/x86/include/uapi/asm/kvm.h
    +++ b/arch/x86/include/uapi/asm/kvm.h
    @@ -362,6 +362,11 @@ struct kvm_xsave {
    __u32 region[1024];
    };

    +/* for KVM_CAP_XSAVE_EXTENSION */
    +struct kvm_xsave_extension {
    + __u32 region[3072];
    +};
    +
    #define KVM_MAX_XCRS 16

    struct kvm_xcr {
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index 15908bc65d1c..bfbde877221e 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -3786,6 +3786,10 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
    case KVM_CAP_XCRS:
    r = boot_cpu_has(X86_FEATURE_XSAVE);
    break;
    + case KVM_CAP_X86_XSAVE_EXTENSION:
    + r = boot_cpu_has(X86_FEATURE_XSAVE) &&
    + boot_cpu_has(X86_FEATURE_XFD);
    + break;
    case KVM_CAP_TSC_CONTROL:
    r = kvm_has_tsc_control;
    break;
    @@ -4395,7 +4399,7 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,

    #define XSTATE_COMPACTION_ENABLED (1ULL << 63)

    -static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
    +static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu, bool has_extension)
    {
    struct xregs_state *xsave;
    struct fpu *guest_fpu;
    @@ -4403,9 +4407,14 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
    u64 valid;

    guest_fpu = vcpu->arch.guest_fpu;
    - xsave = &guest_fpu->state.xsave;
    + xsave = __xsave(guest_fpu);
    xstate_bv = xsave->header.xfeatures;

    + if (!has_extension) {
    + /* truncate with only non-dynamic features */
    + xstate_bv = xstate_bv & ~xfeatures_mask_user_dynamic;
    + }
    +
    /*
    * Copy legacy XSAVE area, to avoid complications with CPUID
    * leaves 0 and 1 in the loop below.
    @@ -4450,7 +4459,7 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
    u64 valid;

    guest_fpu = vcpu->arch.guest_fpu;
    - xsave = &guest_fpu->state.xsave;
    + xsave = __xsave(guest_fpu);

    /*
    * Copy legacy XSAVE area, to avoid complications with CPUID
    @@ -4488,29 +4497,31 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
    }
    }

    -static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
    - struct kvm_xsave *guest_xsave)
    +static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu, u32 *region, bool has_extension)
    {
    if (boot_cpu_has(X86_FEATURE_XSAVE)) {
    - memset(guest_xsave, 0, sizeof(struct kvm_xsave));
    - fill_xsave((u8 *) guest_xsave->region, vcpu);
    + if (has_extension)
    + memset(region, 0, sizeof(struct kvm_xsave_extension));
    + else
    + memset(region, 0, sizeof(struct kvm_xsave));
    +
    + fill_xsave((u8 *)region, vcpu, has_extension);
    } else {
    - memcpy(guest_xsave->region,
    + memcpy(region,
    &vcpu->arch.guest_fpu->state.fxsave,
    sizeof(struct fxregs_state));
    - *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)] =
    + *(u64 *)&region[XSAVE_HDR_OFFSET / sizeof(u32)] =
    XFEATURE_MASK_FPSSE;
    }
    }

    #define XSAVE_MXCSR_OFFSET 24

    -static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
    - struct kvm_xsave *guest_xsave)
    +static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu, u32 *region)
    {
    u64 xstate_bv =
    - *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)];
    - u32 mxcsr = *(u32 *)&guest_xsave->region[XSAVE_MXCSR_OFFSET / sizeof(u32)];
    + *(u64 *)&region[XSAVE_HDR_OFFSET / sizeof(u32)];
    + u32 mxcsr = *(u32 *)&region[XSAVE_MXCSR_OFFSET / sizeof(u32)];

    if (boot_cpu_has(X86_FEATURE_XSAVE)) {
    /*
    @@ -4520,13 +4531,13 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
    */
    if (xstate_bv & ~supported_xcr0 || mxcsr & ~mxcsr_feature_mask)
    return -EINVAL;
    - load_xsave(vcpu, (u8 *)guest_xsave->region);
    + load_xsave(vcpu, (u8 *)region);
    } else {
    if (xstate_bv & ~XFEATURE_MASK_FPSSE ||
    mxcsr & ~mxcsr_feature_mask)
    return -EINVAL;
    memcpy(&vcpu->arch.guest_fpu->state.fxsave,
    - guest_xsave->region, sizeof(struct fxregs_state));
    + region, sizeof(struct fxregs_state));
    }
    return 0;
    }
    @@ -4642,6 +4653,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
    union {
    struct kvm_lapic_state *lapic;
    struct kvm_xsave *xsave;
    + struct kvm_xsave_extension *xsave_ext;
    struct kvm_xcrs *xcrs;
    void *buffer;
    } u;
    @@ -4847,7 +4859,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
    if (!u.xsave)
    break;

    - kvm_vcpu_ioctl_x86_get_xsave(vcpu, u.xsave);
    + kvm_vcpu_ioctl_x86_get_xsave(vcpu, u.xsave->region, false);

    r = -EFAULT;
    if (copy_to_user(argp, u.xsave, sizeof(struct kvm_xsave)))
    @@ -4855,6 +4867,20 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
    r = 0;
    break;
    }
    + case KVM_GET_XSAVE_EXTENSION: {
    + u.xsave_ext = kzalloc(sizeof(struct kvm_xsave_extension), GFP_KERNEL_ACCOUNT);
    + r = -ENOMEM;
    + if (!u.xsave_ext)
    + break;
    +
    + kvm_vcpu_ioctl_x86_get_xsave(vcpu, u.xsave_ext->region, true);
    +
    + r = -EFAULT;
    + if (copy_to_user(argp, u.xsave_ext, sizeof(struct kvm_xsave_extension)))
    + break;
    + r = 0;
    + break;
    + }
    case KVM_SET_XSAVE: {
    u.xsave = memdup_user(argp, sizeof(*u.xsave));
    if (IS_ERR(u.xsave)) {
    @@ -4862,7 +4888,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
    goto out_nofree;
    }

    - r = kvm_vcpu_ioctl_x86_set_xsave(vcpu, u.xsave);
    + r = kvm_vcpu_ioctl_x86_set_xsave(vcpu, u.xsave->region);
    + break;
    + }
    + case KVM_SET_XSAVE_EXTENSION: {
    + u.xsave_ext = memdup_user(argp, sizeof(*u.xsave_ext));
    + if (IS_ERR(u.xsave_ext)) {
    + r = PTR_ERR(u.xsave_ext);
    + goto out_nofree;
    + }
    +
    + r = kvm_vcpu_ioctl_x86_set_xsave(vcpu, u.xsave_ext->region);
    break;
    }
    case KVM_GET_XCRS: {
    diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
    index ca41220b40b8..42a167a29350 100644
    --- a/include/uapi/linux/kvm.h
    +++ b/include/uapi/linux/kvm.h
    @@ -1053,6 +1053,7 @@ struct kvm_ppc_resize_hpt {
    #define KVM_CAP_X86_USER_SPACE_MSR 188
    #define KVM_CAP_X86_MSR_FILTER 189
    #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190
    +#define KVM_CAP_X86_XSAVE_EXTENSION 191

    #ifdef KVM_CAP_IRQ_ROUTING

    @@ -1462,6 +1463,13 @@ struct kvm_s390_ucas_mapping {
    /* Available with KVM_CAP_XSAVE */
    #define KVM_GET_XSAVE _IOR(KVMIO, 0xa4, struct kvm_xsave)
    #define KVM_SET_XSAVE _IOW(KVMIO, 0xa5, struct kvm_xsave)
    +/*
    + * Available with KVM_CAP_XSAVE_EXTENSION
    + * 0xa4/0xa5 are ok for the new ioctls since structure size is different.
    + */
    +#define KVM_GET_XSAVE_EXTENSION _IOW(KVMIO, 0xa4, struct kvm_xsave_extension)
    +#define KVM_SET_XSAVE_EXTENSION _IOW(KVMIO, 0xa5, struct kvm_xsave_extension)
    +
    /* Available with KVM_CAP_XCRS */
    #define KVM_GET_XCRS _IOR(KVMIO, 0xa6, struct kvm_xcrs)
    #define KVM_SET_XCRS _IOW(KVMIO, 0xa7, struct kvm_xcrs)
    --
    2.18.4
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